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Scheduler: ""approaching astronomical twilight rise limit" around midnight?

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Hi!

I've seen this a few times lately and really don't know what to make of it. I have a Stellarmate 1.5. I have a list of around 20 jobs, mostly variable stars. Just after midnight, the next job i queue is paused with this message:
""Job 'IX Lyr' is now approaching astronomical twilight rise limit"
And it stays that way for the rest of the night.

I have set the dusk and dawn limits to be very "non-restrictive" to allow imaging very early and quite late, as this is less of a problem with variable stars than deep sky objects, and as our dusk and dawn in Sweden now are very long (approaching summer bright nights). The settings this night had dusk at 22.00 and dawn at 03:00, as read from the scheduler window. So why this job thinks twilight is approaching at around 00:00 is a bit mysterious to me. Anyone can help me understand this? I guess it is a question of settings that I have not gotten right. Attached is the kstars log and the job file.

Magnus
3 years 10 months ago #53390
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The dusk and dawn limits are relative to the start and end of astronomical twilight and for you it could be that it now never gets astronomically dark. If it doesn't then limits relative to it can't be set. All you can do is uncheck the Twilight box.
3 years 10 months ago #53393

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Hi!

Thanks for your reply! However:

I understand the times given in the scheduler for dusk and dawn as the times that Ekos has calculated - is that not correct?

I mean, surely, at 22:00 the sky is not astronomically dark. This is a time Ekos has calculated based on my location and my settings of dusk and dawn offsets. If I change the offsets, these times changes accordingly. So: are not these calculated values what determines the dusk and dawn in Ekos?

And if so: when I have the values 22:00 and 03:00 - why does this single job think that dawn is approaching 3 hours before the time given by the Scheduler? I just don't get it.

Magnus
3 years 10 months ago #53394

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There is something I'm not sure I understand from the log: at line 422, the host time suddenly changes from 11:31 to 21:30. Is this a delayed time synchronisation? Mmmh, gps-based time when the INDI driver is connected, isn't it?
After that, the Scheduler is trying to schedule observations starting at 11:31, as if KStars still had the previous time.
I wonder if that could be the issue. In any case, it shows that Scheduler is trusting a variable that contains an outdated time value for too long.
However, I am not sure that situation is the direct cause for the pre-dawn time to remain stuck to midnight, that's weird...

EDIT: The twilight restriction already take the astronomical dawn and dusk into account, plus the pre-dawn safety margin in the Ekos options.
Last edit: 3 years 10 months ago by Eric.
3 years 10 months ago #53407

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Hi!

Thanks! Interesting!!!

When I started Kstars, time was way off. I have no idea why. I had not changed it since the night before. ANd I have no GPS unit updating it - it is only Kstars relying on system time. So I clicked on the clock in Kstars, clicked "Now" and it set the time right. After that, I did nothing to adjust the time.

Is there a way I can look into that more? ANy indication of why this happened? (I was asleep at least)

So I can rely on the times I read in the Schedular tab, right? Those are the values that the Scheduler will evaluate against, if I get it right.

Magnus
Last edit: 3 years 10 months ago by Magnus Larsson.
3 years 10 months ago #53408

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Hi!

This adds to my mystery right now. I am setting up the scheduler for tonight's jobs. ANd I have deselected twilight restrictions for all, instead set an end time for the last job. But something odd seems to happen around midnight. Whichever job it is that lands there is rendered invalid or aborted - and next jobs are set to start.... earlier rather than later. See attached screenshot.



What am I doing to produces this?

Magnus
Last edit: 3 years 10 months ago by Magnus Larsson.
3 years 10 months ago #53444
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If all subsequent nights have no astronomical dark then the next time there will be astronomical night could be six to eight weeks ahead. A couple of hours delay before that means six to eight weeks less two hours. I've no idea how the software copes with this.

What's actually wanted is a change to the astronomical dark limit, from 8 degrees to something less. Changing the delays is adjusting things in the wrong direction.

No amount of rhetoric will change the inclination of the earth's axis - and if it did everyone's polar axis alignment would be screwed up.
3 years 10 months ago #53445

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Hi Chris!

I think I follow you - nights are simply not dark enough. But does Ekos care when I have disabled the twilight restriction?

What I want to do is image even if it is not astronomically dark. What am I doing wrong? Feel confused....

Magnus
3 years 10 months ago #53446

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Do what I said in my first reply, uncheck the Twilight box.
3 years 10 months ago #53449

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Hi!

Yeah, I did! In the last post, and tonights jobs, there are no jobs with twilight checked. Let's see what happens. But then what is that odd thing in my screenshot?

Magnus
3 years 10 months ago #53450

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Ah, OK, sorry, found the errror and fixed it. User error again.

Let's see how it goes now.

Magnus
3 years 10 months ago #53451

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Chris, I'm sorry, I didn't understand what your point was. You are stating there are very short astronomical nights up there in Sweden, which I agree with. Ekos is however calculating the dusk-dawn interval based on the altitude of Sun, and finds there is actually an astronomical night (be it correct or not). As far as Ekos is concerned, it should obviously allow observation between midnight and 3:00am, because it uses an interval test, therefore there is a bug lying in there. Now I agree with your solution to Magnus, which is to disable the twilight restriction, but I just wanted to clarify?

-Eric
3 years 10 months ago #53518

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